Abstract: The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centers, for improving its color. The method includes preblocking and preshaping a discolored natural diamond to prevent its breakage in a high pressure/high temperature (HP/HT) press, placing said discolored natural diamond in a pressure transmitting medium which is consolidated into a pill. Next, the pill is placed into a HP/HT press at elevated pressure and elevated temperature within the graphite-stable or diamond-stable range of the carbon phase diagram for a time sufficient to improve the color of said diamond. Finally, the diamond is recovered from said press. Colorless and fancy colored diamonds can be made by this method.

Abstract: The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centers, for improving its color. The method includes placing a discolored natural diamond in pressure transmitting medium powder which is consolidated into a pill. Next, the pill is placed into a high pressure/high temperature (HP/HT) press at elevated pressure and elevated temperature within the diamond stable range of the carbon phase diagram for a time sufficient to improve the color of said diamond. Finally, the diamond is recovered from said press. Colorless diamond can be made by this method.

Abstract: A method for treating diamond for improving the oxidation resistance and the mechanical strength of said diamond crystals includes forming a mixture of diamond crystals, a source of boron, and inert particles. This mixture is heated at a temperature of between about 800° and 1200° C. for a time adequate to diffuse boron into the surface of the diamond crystals for improving the oxidation resistance and the mechanical strength of the boron-diffused diamond crystals. The resulting diamond crystals have improved oxidation resistance and improved mechanical strength by virtue of having had boron thermally diffused into the surface of thereof.

Abstract: A method for treating as as-grown chemical vapor deposited (CVD) starting diamond film having stresses and containing voids, comprises the step of subjecting the diamond film to a temperature of above about 1000.degree. C. and a hydrostatic pressure of above about 3 kilobars.

Abstract: A composite diamond wire die for drawing wire has a single crystal or HTHP diamond substrate and a CVD layer or layers deposited thereon. A wire die bore extends through the substrate and between the CVD layers, with a wire bearing surface being located completely within the substrate. The CVD layers may be deposited so as to develop tensile stress therein, so as to place the substrate in compression.

Abstract: A composite diamond wire die for drawing wire has a single crystal or HTHP diamond substrate and a CVD layer or layers deposited thereon. The wire die bore extends through the diamond substrate, and the substrate is surrounded by the diamond CVD layer.

Abstract: A composite diamond wire die for drawing wire has a single crystal or HTHP diamond substrate and a CVD layer or layers deposited thereon. The wire die bore extends through both the substrate and the CVD layers, with the wire bearing surface being located within the substrate.

Abstract: An annular body, which may be a die for drawing wire, comprises an annular transparent CVD diamond body having an opening of uniform diameter with an interior surface in a region of smaller diamond grains and an external surface in a region of larger diamond grains.

Abstract: Broadly, the present invention is directed to polycrystalline diamond of improved thermal conductivity. The novel polycrystalline diamond consists essentially of at least 99.5 wt-% isotopically-pure carbon-12 or carbon-13. The inventive polycrystalline diamond is formed from at least 99.5 wt-% isotopically-pure carbon-12 or carbon-13. Single-crystal isotopically-pure carbon-12 and carbon-13 diamond are known to possess improved thermal conductivity. Polycrystalline diamond, however, possesses lower thermal conductivity patterns deleteriously impacted by, for example, impurities, isotopic effects, and grain boundary scattering. In fact, grain boundary scattering would lead the skilled artisan to believe that the thermal conductivity of polycrystalline diamond would be substantially unaffected by the isotopic nature of the diamond itself.

Abstract: Chemical vapor deposition method for producing a fine grained smooth growth surfaced diamond film on a substrate employs a hydrogen/hydrocarbon gaseous atmosphere containing an amount of nitrogen effective to inhibit the growth of the diamond grains deposited on the substrate.

Abstract: Graphite is employed as a heat sink material, preferably with its c-planes perpendicular to the surface on which the heat-generating source is mounted at least in the portion in immediate contact with said source. The thermal conductivity of the graphite may be increased by heat treatment or by making it isotopically pure.

Abstract: Thermal drug treatment of tumor tissue is obtained by attaching a thermally active drug to carrier molecules which have an affinity to tumor tissue. Localized heating is performed on the tumor tissue, thereby activating the drug in the tumor tissue. The end result may be concentrated delivery of a drug to a chosen tissue, or, in the case where the drug creates a toxin when heated, selective tissue destruction of a selected locations heated. The localized heat may be applied by focused ultrasound heating.

Abstract: A method for producing CVD diamond film on a substrate comprised of a hydride-forming metal. The substrate provides for easy release of the CVD diamond coating formed thereon upon exposure to a hydrogen pressure. Self-supporting CVD diamond films of large dimension are easily obtained without dissolving the substrate. The substrate can be used in conventional CVD reactors.

Abstract: An apparatus for annealing diamond water jet mixing tubes comprises an enclosure, a vertical cylindrical heating tube in the enclosure, a heater for the heating tube and a rack in the heating tube to support the diamond mixing tube. Annealing relieves internal tensile stresses which can decrease the life of the mixing tube.

Abstract: A die for drawing wire of a predetermined diameter comprising an optically non-opaque CVD diamond body having a thermal conductivity greater than 4 watts/cm-K with an opening extending through said body and having a wire bearing portion of substantially circular cross-section determinative of the diameter of the wire.

Abstract: Broadly, the present invention is directed to improving a chemical vapor phase deposition (CVD) method for synthesis of diamond wherein a hydrocarbon/hydrogen gaseous mixture is subjected to a combustion flame in the presence of oxygen to at least partially decompose the gaseous mixture to form CVD diamond. The improvement in process comprises subjecting said combustion flame to one or more of dielectric heating, d.c. discharge, or a.c. discharge. Dielectric heating can be accomplished by subjecting the combustion flame to microwave (MW) frequency discharge or radiofrequency (RF) discharge. By superimposing dielectric heating or d.c./a.c. discharge plasma generation on combustion flame process, the carbon utilization rate of the combustion flame process should improve substantially.

Abstract: A stress relieved CVD diamond is produced by annealing said CVD diamond at a temperature above about 1100 to about 2200 degrees Centigrade in a non-oxidizing atmosphere at a low pressure or vacuum and for a suitable short period of time which decreases with increasing annealing temperature so as to prevent graphitization of said diamond.

Abstract: Diamond workpieces comprised of polycrystalline CVD diamond having a grain size of less than 1 .mu.m are provided. These diamond workpieces are more resistant to wear and are more conducive to polishing than conventional diamond workpieces having large-grain diamonds. Three-dimensional workpieces such as water jet nozzles and water jet mixing tubes comprised of the small-grain diamonds provide particular advantage in that they can be easily finished to a final size and shape.

Abstract: Diamond is produced by chemical vapor deposition on a substrate by hot filament activation of a hydrogen-hydrocarbon gas mixture. An edge of the substrate faces the filament at a distance therefrom up to about 1 mm and preferably about 0.3-0.7 mm., and the substrate is moved relative to the filament to maintain this spacing as diamond forms thereon. Diamond formation proceeds at an improved rate, and in single crystal configuration under certain conditions.

Abstract: Chemical vapor deposition of diamond with <100> orientation and (100) growth facets is performed at an increased growth rate and affords cubic diamond crystals when a gas mixture comprising hydrogen, a hydrocarbon such as methane and specific minor amounts of oxygen and an inert gas, preferably predominantly nitrogen, is employed.